Aplicação de ferramentas da metodologia Seis Sigma no estudo investigativo de medição do teor de carbono do ferro fundido no processo de fundição

Abstract

This paper reports issues regarding the Six Sigma working methodology applied on an investigation project with emphasis on the use of specific tools seeking for answers and the knowledge development. The workplace is an iron-casting foundry where there was the need of finding elements that would influence on the metal chemical content stabilization, with focus on carbon percentage. The applied methodology is based on investigation tools and cyclic learning (PDSA). Among the tools, some are highlighted: TMAP (Thought Map); Process Map; MSE (Measurement System Evaluation) and DOE (Design of Experiments). It is a long investigation and goes through several kinds of analysis. The sequential approach is prevailing through the every step conclusions and main learns. The chemical content of a metal sample is evaluated by OES (Optical Emission Spectrometry) which is made by a spectrometer. The equipment accuracy is evaluated mainly by metal samples that are certified worldwide, the socalled patterns. This paper brings several sampling plans and many variation sources of the whole process that comes out with some critical methods, which barrel the actual activities, made in the foundry building. By ending the analysis a new theory rises up, the equipment calibration frequency is very important in order to guarantee a maximal acceptable natural measurement variation. This conclusion was made by changing the calibration method after several learns regarding the process of chemical composition measurement. This specific conclusion implies on further studies about finding the manner of maintaining the spectrometers stabilization.